Twelve RYGB candidates who were successfully treated with an SRI for primary mood or anxiety disorders were studied prospectively. Blood samples for SRI plasma levels were drawn immediately after dose for pharmacokinetic studies (PK) preoperatively. Maximum concentration (CMAX), time to CMAX (TMAX), and Area Under Concentration/Time curve (AUC) were determined. PK studies were repeated at one, six, and twelve months post-operatively. PK data were corrected for dose at each study time point. The Structured Interview Guide for the Hamilton Depression Rating Scale— Atypical Depression Symptom Version was used to quantify depressive symptoms.